Photographic diffusion transfer color process and composite film unit for use therein

ABSTRACT

THE INVENTION RELATES TO A COMPOSITE PHOTOGRAPHIC FILM UNIT STRUCTURE WHICH COMPRISES A PLURALITY OF ESSENTIAL LAYERS INCLUDING, IN SEQUENCE, A FIRST DIMENSIONALLY STABLE, LIQUID IMPERMEABLE LAYER; ONE OR MORE SILVER HALIDE EMULSION LAYERS EACH HAVING ASSOCIATED THEREWITH A DYE IMAGEFORMING MATERIAL WHICH IS SOLUBLE AND DIFFUSIBLE DURING PROCESSING, AS A FUNCTION OF THE EXPOSURE OF ITS ASSOCIATED SILVER HALIDE EMULSION LAYER, AT A FIRST SOLVENT CONCENTRATION; A POLYMERIC LAYER DYEABLE BY THE DYE IMAGE-PROVIDING MATERIALS; AND A SECOND DIMENSIONALLY STABLE, LIQUID IMPERMEABLE TRANSPARENT LAYER. THE FILM UNIT STRUCTURE ADDITIONALLY INCLUDES MEANS SECURING THE RESPECTIVE LAYERS IN SUBSTANTIALLY FIXED RELATIONSHIP AND THE DIMENSIONALLY STABLE SUPPORT LAYERS, TAKEN TOGETHER, POSSESS A PROCESSING COMPOSITION SOLVENT VAPOR PERMEABILITY SUFFICIENT TO EFFECT, SUBSEQUENT TO SUBSTANTIAL DYE TRANSFER IMAGE FORMATION BY DIFFUSION TRANSFER PROCESSING AND PRECEDING SUBSTANTIAL ENVIRONMENTAL DYE TRANSFER IMAGE DEGRADTION, OSMOTIC TRANSPIRATION OF PROCESSING COMPOSITION SOLVENT IN A QUANTITY EFFECTIVE TO DECREASE THE FIRST SOLVENT CONCENTRATION AT WHICH THE DYE IMAGE-FORMING MATERIAL IS SOLUBLE AND DIFFUSIBLE TO A SECOND SOLVENT CONCENTRATION AT WHICH THE DYE IMAGEFORMING MATERIAL IS SUBSTANTIALLY NONDIFFUSIBLE. THE STRUCTURE ALSO INCLUDES A RUPTURABLE CONTAINER RETAINING PROCESSING COMPOSITION IN A QUANTITY SUFFICIENT TO PROVIDE THE FIRST SOLVENT CONCENTRATION AND, PREFERABLY, OPACIFYING AGENT IN A QUANTITY SUFFICIENT TO MASK DYE IMAGE-FORMING MATERIAL ASSOCIATED WITH THE SILVER HALIDE EMULSIONS MOUNTED TRANSVERSE A LEADING EDGE OF THE STRUCTURE TO EFFECT DISCHARGE OF THE CONTAINER&#39;&#39;S CONTENTS BETWEEN THE DYEABLE POLYMERIC LAYER AND NEXT ADJACENT SILVER HALIDE EMULSION LAYER DURING PHOTOGRAPHIC DIFFUSION TRANSFER COLOR PROCESSING IN ACCORDANCE WITH THE INVENTION.

3,513,044 COMPOSITE Mz'irh'SO, T971 H. LAND PHOTOGRAPHIC DIFFUSIONTRANSFER COLOR PROCESS AND I FILM UNIT FOR USE THEREIN Filed Dec. 9,1968 4 Sheets-$heet 1 FIG. I

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ATTORNEYS @Mw n/ mm w wI United States Patent M PHOTOGRAPHIC DIFFUSIONTRANSFER COLOR PROCESS AND COMPOSITE FILM UNIT FOR USE THEREIN Edwin H.Land, Cambridge, Mass., assignor to Polaroid Corporation, Cambridge,Mass. Filed Dec. 9, 1968, Ser. No. 782,075 Int. Cl. C03c 7/00 US. Cl.963 34 Claims ABSTRACT OF THE DISCLOSURE The invention relates to acomposite photographic film unit structure which comprises a pluralityof essential layers including, in sequence, a first dimensionallystable, liquid impermeable layer; one or more silver halide emulsionlayers each having associated therewith a dye imageforming materialwhich is soluble and diffusible during processing, as a function of theexposure of its associated silver halide emulsion layer, at a firstsolvent concentration; a polymeric layer dyeable by the dyeimage-providing materials; and a second dimensionally stable, liquidimpermeable transparent layer.

The film unit structure additionally includes means securing therespective layers in substantially fixed relationship and thedimensionally stable support layers, taken together, possess aprocessing composition solvent vapor permeability sufficient to effect,subsequent to substantial dye transfer image formation by diffusiontransfer processing and preceding substantial environmental dye transferimage degradation, osmotic transpiration of processing compositionsolvent in a quantity effective to decrease the first solventconcentration at which the dye image-forming material is soluble anddiffusible to a second solvent concentration at which the dyeimageforming material is substantially nondiffusible.

The structure also includes a rupturable container retaining processingcomposition in a quantity sufficient to provide the first solventconcentration and, preferably, opacifying agent in a quantity sufficientto mask dye image-forming material associated with the silver halideemulsions mounted transverse a leading edge of the structure to effectdischarge of the containers contents between the dyeable polymeric layerand next adjacent silver halide emulsion layer during photographicdiffusion transfer color processing in accordance with the invention,

The present invention relates to photography and, more particularly, tophotographic products particularly adapted for employment inphotographic diffusion transfer color processes.

The primary objects of the present invention are to provide photographicproducts particularly adapted for employment in diffusion transfer colorprocesses; to provide photographic products which comprise aphotosensitive composite structure which contains a plurality ofessential layers including a first dimensionally stable, liquidimpermeable layer, a photosensitive silver halide emulsion layer havinga dye image-forming material associated therewith which is soluble anddiffusible at a first processing composition solvent concentration, apolymeric layer dyeable by the dye image-forming material, and a seconddimensionally stable, liquid impermeable layer, transparent to incidentradiation, wherein the dimensionally stable, liquid impermeable layerstaken together possess a processing composition solvent vaporpermeability sufficient to effect, subsequent to substantial transferimage formation by diffusion transfer processing and precedingsubstantial environmental transfer image degradation, osmotictranspiration of processing compo- 3,573,044 Patented Mar. 30, 1971sition solvent in a quantity effective to decrease the first solventconcentration to a second solvent concentration at which the dyeimage-forming material is substantially nondiffusible; to providephotographic diffusion transfer products comprising a film unitincluding a composite photosensitive structure of the last-identifiedtype in combination with a rupturable container retaining a processingcomposition comprising the solvent; to provide a diffusion transfer filmunit of the last-identified type having the container fixedly positionedand extending transverse a leading edge of the composite photosensitivestructure whereby to effect, upon application of compressive pressure,discharge of the processing composition intermediate the dyeablepolymeric layer and photo-sensitive silver halide emulsion next adjacentthereto in a quantity sufiicient to provide the first solventconcentration; to'provide a diffusion transfer color film unit of thelast-identified type including an opacifying agent disposed intermediatethe dyeable polymeric layer and the photosensitive emulsion nextadjacent thereto in a quantity sufficient to mask the dye image-formingmaterial; to provide a diffusion transfer color film unit of thelast-identified type possessing the opacifying agent initially presentin the processing composition for discharge intermediate the dyeablepolymeric layer and the photosensitive silver halide emulsion nextadjacent thereto upon application of compressive pressure to thecontainer and distribution of its contents intermediate the layers; andto provide photographic diffusion transfer color processes employingsuch products.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the product possessing the features,properties and the relation of components and the process involving theseveral steps and the relation and order of one or more of such stepswith respect to each of the others which are exemplified in thefollowing detailed disclosure, and the scope of the application of whichwill be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a photographic film unit embodying theinvention;

FIGS. 2, 4 and 6 are diagrammatic enlarged cross-sectional views of thefilm unit of FIG. 1, along section line 2- 2, illustrating theassociation of elements during the three illustrated stages of theperformance of a diffusion transfer process, for the production of amuticolor transfer image according to the invention, the thickness ofthe various materials being exaggerated, and wherein FIG. 2 representsan exposure stage, FIG. 4 represents a processing stage and FIG. 6represents a product of the process; and

FIGS. 3, 5 and 7 are diagrammatic, further enlarged cross-sectionalviews of the film unit of FIGS. 2, 4 and 6, along section lines 33, 55and 7-7, respectively, further illustrating, in detail, the arrangementof layers comprising the photosensitive laminate during the threeillustrated stages of the transfer process.

As disclosed in US. Pat. No. 2,983,606, issued May 9, 1961, aphotosensitive element containing a dye developer, that is, a dye whichis a silver halide developing agent, and a silver halide emulsion may beexposed and wetted by a liquid processing composition, for example, byimmersion, coating, spraying, flowing, etc., in the dark, and theexposed photosensitive element superposed prior to, during, or afterwetting, on a sheetlike support element which may be utilized as animage-receiving element. In a preferred embodiment, the liquidprocessing composition is applied to the photosensitive element in asubstantially uniform layer as the photosensitive element is broughtinto superposed relationship with the image-receiving layer. The liquidprocessing composition, positioned intermediate the photosensitiveelement and the imagereceiving layer, permeates the emulsion to initiatedevelopment of the latent image contained therein. The dye developer isimmobilized or precipitated in exposed areas as a consequence of thedevelopment of the latent image. This immobilization is apparently, atleast in part, due to a change in the solubility characteristics of thedye developer upon oxidation and especially as regards its solubility inalkaline solutions. It may also be due in part to a tanning effect onthe emulsion by oxidized developing agent, and in part to a localizedexhaustion of alkali as a result of development. In unexposed andpartially exposed areas of the emulsion, the dye developer is unreactedand diffusible and thus provides an imagewise distribution of unoxidizeddye developer dissolved in the liquid processing composition, as afuction of the point-to-point degree of exposure of the silver halideemulsion. At least part of this imagewise distribution of unoxidized dyedeveloper is transferred, by imbibition, to a superposed image-receivinglayer or element, said transfer substantially excluding oxidized dyedeveloper. The image-receiving element receives a depth-Wise diffusion,from the developed emulsion, of unoxidized dye developer withoutappreciably disturbing the imagewise distribution thereof to provide thereversed or positive color image of the developed image. Theimage-receiving element may contain agents adapted to mordant orotherwise fix the diffused, unoxidized dye developer. If the color ofthe transferred dye developer is affected by changes in the pH of theimagereceiving element, this pH may be adjusted in accordance withwell-known techniques to provide a pH affording the desired color. Thedesired positive image is revealed by stripping the image-receivinglayer from the photosensitive element at the end of a suitableimbibition period.

The dye developers, as noted above, are compounds which contain, in thesame molecule, both the chromophoric system of a dye and also a silverhalide developing function. By a silver halide developing function ismeant a grouping adapted to develop exposed silver halide. A preferredsilver halide development function is a hydroquinonyl group. Othersuitable developing functions include ortho-dihydroxyphenyl and orthoandpara-amino substituted hydroxyphenyl groups. In general, the developmentfunction includes a benzenoid developing function, that is, an aromaticdeveloping group which forms quinonoid or quinone substances whenoxidized.

Multicolor images may be obtained using color imageforming componentssuch as, for example, the previously mentioned dye developers, indiffusion transfer processes by several techniques. One such techniquecontemplates obtaining multicolor transfer images utilizing dyedevelopers by employment of an integral multilayer photosensitiveelement, such as is disclosed in the aforementioned U.S. Pat. No.2,983,606, and particularly with reference to FIG. 9 of the patentsdrawing, wherein at least two selectively sensitized photosensitivestrata, superposed on a single support, are processed, simultaneouslyand without separation, with a single, common image-receiving layer. Asuitable arrangement of this type comprises a support carrying ared-sensitive silver halide emulsion stratum, a green-sensitive silverhalide emulsion stratum and a blue-sensitive silver halide emulsionstratum, said emulsions having associated therewith, respectively, forexample, a cyan dye developer, a magenta dye developer and a yellow dyedeveloper. The dye developer may be utilized in the silver halideemulsion layer, for example, in the form of particles, or it may beemployed as a layer behind the appropriate silver halide emulsionstrata. Each set of silver halide emulsion and associated dye developerstrata are disclosed to be optionally separated from other sets bysuitable interlayers, for example, by a layer of gelatin or polyvinylalcohol. In certain instances, it may be desirable to incorporate ayellow filter in front of the green-sensitive emulsion and such yellowfilter may be incorporated in an interlayer. However, where desirable, ayellow dye developer of the appropriate spectral characteristics andpresent in a state capable of functioning as a yellow filter may beemployed. In such instances, a separate yellow filter may be omitted.

The dye developers are preferably selected for their ability to providecolors that are useful in carrying out subtractive color photography,that is, the previously mentioned cyan, magenta and yellow. The dyedevelopers employed may be incorporated in the respective silver halideemulsion or, in the preferred embodiment, in a separate layer behind therespective silver halide emulsion. Specifically, the dye developer may,for example, be in a coating or layer behind the respective silverhalide emulsion and such a layer of dye developer may be applied by useof a coating solution containing about 0.5 to 8%, by weight, of therespective dye developer distributed in a film-forming natural, orsynthetic, polymer, for example, gelatin, polyvinyl alcohol, and thelike, adapted to be permeated by the chosen diffusion transfer fluidprocessing composition.

As examples of materials, for use as the image-receiving layer, mentionmay be made of solution dyeable polymers such as nylon as, for example,N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzedpolyvinyl acetate; polyvinyl alcohol with or without plasticizers;cellulose acetate with filler as, for example, one-half celluloseacetate and one-half oleic acid; gelatin; and other materials of asimilar nature. Preferred materials comprise polyvinyl alcohol orgelatin containing a dye mordant such as poly-4-vinylpyridine, asdisclosed in U.S. Pat. No. 3,148,061, issued Sept. -8, 1964.

As disclosed in the previously cited patents, the liquid processingcomposition referred to for effecting multicolor diffusion transferprocesses comprises at least an aqueous solution of an alkalinematerial, for example, diethylamine, sodium hydroxide or sodiumcarbonate and the like, and preferably possessing a pH in excess of 12,and most preferably includes a viscosity-increasing compoundconstituting a film-forming material of the type which, when thecomposition is spread and dried, forms a relatively firm and relativelystable film. The preferred filmforming materials disclosed comprise highmolecular weight polymers such as polymeric, water-soluble ethers whichare inert to an. alkaline solution such as, for example, a hydroxyethylcellulose or sodium carboxymethyl cellulose. Additionally, film-formingmaterials or thickening agents whose ability to increase viscosity issubstantially unaffected if left in solution for a long period of timeare also disclosed to be capable of utilization. As stated, thefilm-forming material is preferably contained in the processingcomposition in such suitable quantities as to impart to the compositiona viscosity in excess of cps. at a temperature of approximately 24 C.and preferably in the order of 100,000 cps. to 200,000 cps. at thattemperature.

In accordance with aforementioned U.S. Pat. No. 2,983,- 606, animage-receiving layer of the type disclosed in that patent need not beseparated from its superposed contact with the photosensitive element,subsequent to transfer image formation, if the image-receiving elementis transparent and a processing com osition containing a substancerendering the processing composition layer opaque is spread between theimage-receiving layer and the silver halide emulsion or emulsions.

However, it has been found, if the image-receiving element is maintainedin contact with the photosensitive element, subsequent to dye developertransfer image formation, and includes the presence of an alkalineprocessing composition, necessarily having a pH at which dye developer,for example, in reduced form, diffuses to form the dye transfer image,intermediate the elements, the transfer image thus formed in unstableover an extended period of time. The dye image instability is due, atleast in part to the presence of what is, in general, a relatively highpH alkaline composition in intimate contact with the dye or dyes formingthe image. This contact itself provides instability to the molecularstructure of dye by, for example, catalyzing degradation and undesirablestructural shifts effecting the spectral absorption characteristics ofthe image dye. In addition, the presence of an alkaline composition,possessing a pH at which the dye, for example, in reduced form,diffuses, also provides an integral dynamic system wherein oxidized dye,immobilized in areas of the photosensitive element, as a function of itsdevelopment, with the passage of time attempts to generate, in suchareas, an equilibrium between oxidized and reduced dye. In that the pHof the dynamic system is such that diffusion of the reduced form of thedye will occur, such reduced dye will, at least in part, transfer to theimage-receiving layer and the resultant diffusion will imbalance theequlibrium, in such areas of the photosensitive element, in favor ofadditional formation of reduced dye. As a function of the efficiency ofthe image-receiving layer, as a dye sink, such nonimagewise dyeing ofthe image-carrying layer still further imbalances the equilibrium infavor of the additional formation of dye in reduced, diffusible form.Under such circumstances, the transfer image definition, originallycarried by the image-receiving layer, will suffer a continuous decreasein the delta between the images maximum and minimum densities and may,ultimately, result in the image-receiving elements loss of all semblanceof image definition; merely becoming a polymeric stratum carrying arelatively uniform overall dyeing.

Any attempt to decrease the dye sink capacity of the image-carryinglayer, for example, by reduction of its mordant capacity, in order toalleviate, at least to an extent, the action of the image-receivinglayer as a dye sink, however, will enhance diffusion of the dye,comprising the transfer image, from the image-carrying layer, to theremainder of the element due, at least in part, to the continuedpresence of the alkaline composition having a pH at which the reducedform of the dye, forming the transfer image, is diffusible. The ultimateresult is substantially the same overall image distortion as occurs whenthe image-receiving layer acts as a dye sink, with the exception thatthe dye is more extensively distributed throughout the film unit and theultimate overall dyeing of the image-receiving layer itself is of lowersaturation.

The problems inherent in fabricating a film unit of the type wherein theimage-receiving element, the alkaline processing composition and thephotosensitive element are maintained in contiguous contact subsequentto dye transfer image formation, for example, a film unit of the typedescribed hereinbefore with reference to aforementioned US. Pat. No.2,983,606, may be effectively obviated by fabrication of a film unit inaccordance with the physical parameters specifically set forth incopending US. applications Ser. Nos. 622,283; 622,298 and 638,817, filedMar. 10, Mar. 10 and May 16, 1967, respectively, in the name of Edwin H.Land, now US. Pats. Nos. 3,415,644, 3,415,645, and 3,415,646,respectively, issued Dec. 10, 1968.

Specifically, an integral photographic film unit particularly adaptedfor the production of a dye transfer image of unexpectedly improvedstability and other properties, by a color diffusion transfer processwill be constructed, for example, in accordance with aforementionedcopending US. application Ser. No. 622,283, to include a photosensitiveelement comprising a laminate having, in sequence, as essential layers,a dimensionally stable opaque layer; a photosensitive silver halideemulsion layer having associated therewith dye image-providing materialwhich is soluble and diffusible, in alkali, at a first pH; an alkalinesolution permeable polymeric layer dyeable by the dye image-providingmaterial; a polymeric acid layer containing sufficient acidifying groupsto effect reduction, subsequent to substantial transfer dye imageformation, of a selected processing solution having the first pH to asecond pH at which said dye image-providing material is insoluble andnondiffusible; and a dimensionally stable transparent layer. Incombination with the laminate, a rupturable container retaining anaqueous alkaline processing composition having the first pH andcontaining an opacifying agent, in a quantity sufficient to mask the dyeimage-providing material, is fixedly positioned and extends transverse aleading edge of the laminate whereby to effect unidirectional dischargeof the containers contents between the alkaline solution permeable anddyeable polymeric layer and the photosensitive silver halide emulsionlayer next adjacent thereto, upon application of compressive force tothe container.

It will also be recognized that the dimensionally stable polymericsupport layer next adjacent the photosensitive silver halide emulsionlayer or layers may be transparent, as disclosed in aforementionedcopending US. application Ser. No. 638,817, and that in such instancethe opacifying agent may be initially dispersed in the composite filmunit intermediate the dyeable polymeric layer and the silver halideemulsion layer next adjacent, as disclosed in aforementioned copendingUS application Ser. No. 622,298.

Employment of the last-mentioned film units, according to the describedcolor diffusion transfer photographic process, specifically provides forthe production of a highly stable color transfer image accomplished, atleast in part, by effectively obviating the previously discusseddisadvantages of the prior art products and processes, by in processadjustment of the environmental pH of the film unit from a pH at whichtransfer processing is operative to a pH at which dye transfer isinoperative subsequent to substantial transfer image formation. Thestable color transfer image is obtained irrespective of the fact thatthe film unit is maintained as an integral laminate unit duringexposure, processing, viewing, and storage of the unit, which transferimage exhibits the required maximum and minimum dye transfer imagedensities, dye saturation, hues and definition.

However, film units fabricated in accordance with the parameters setforth above specifically require the presence of the stated polymericacid component to effect in situ process adjustment of the film unitsoperational pH range.

Specifically, the film units require the presence of a polymeric acidlayer such as, for example, of the type et forth in US. Pat. No.3,362,819 which, most preferably, includes the presence of an inerttiming or spacer layer intermediate the polymeric acid layer carried ona support and the image-receiving layer.

As set forth in the last-mentioned patent, the polymeric acid layercomprises polymers which contain acid groups, such as carboxylic acidand sulfonic acid groups, which are capable of forming salts with alkalimetals, such as sodium, potassium etc., or with organic bases,particularly quaternary ammonium bases, such as tetramethyl ammoniumhydroxide or potentially acid-yielding groups, such as anhydrides orlactones, or other groups which are capable of reacting with bases tocapture and retain them. The acid-reacting group is, of course,nondiffusible from the acid polymer layer. In the preferred embodimentsdisclosed, the acid polymer contains free carboxyl groups and thetransfer processing composition employed contains a large concentrationof sodium and/or potassium ions. The acid polymers stated to be mostuseful are characterized by containing free carboxyl groups, beinginsoluble in water in the free acid form, and by forming water-solublesodium and/or potassium salts. One may also employ polymers containingcarboxylic acid anhydride groups, at least some of which preferably havebeen converted to free carboxyl groups prior to imbibition.

While the most readily available polymeric acids are derivatives ofcellulose or of vinyl polymers, polymeric acids from other classes ofpolymers may be used. As examples of specific polymeric acids set forthin the application, mention may be made of dibasic acid halfesterderivatives of cellulose which derivatives contain free carboxyl groups,e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogenglutarate, cellulose acetate hydrogen succinate, ethyl cellulosehydrogen succinate, ethyl cellulose acetate hydrogen succinate,cellulose acetate hydrogen succinate hydrogen phthalate; ether and esterderivatives or cellulose modified with sulfoanhydrides, e.g., withortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethylcellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogenphthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxyor sulfo substituted aldehydes, e.g., m-, or pbenzaldehyde sulfonic acidor carboxylic acid; partial esters of ethylene/maleic anhydridecopolymers; partial esters of methyl-vinyl ether/maleic anhydridecopolymers; etc.

As previously noted, the pH of the processing composition preferably isof the order of at least 12 to 14. The acid polymer layer is disclosedto contain at least sufficient acid groups to effect a reduction in thepH of the image layer from a pH of about 12 to 14 to a pH of at least 11or lower at the end of the imbibition period, and preferably to a pH ofabout to 8 within a short time after imbibition, thus requiring, ofcourse, that the action of the polymeric acid be accurately socontrolled as not to interfere with either development of the negativeor image transfer of unoxidized dye developers. For this reason, the pHof the image layer must be kept at a functional transfer level, forexample, 12 to 14 until the dye image has been formed after which the pHis reduced very rapidly to a pH below that at which dye transfer may beaccomplished, for example, at least about 11 and preferably about pH 9to 10. Unoxidized dye developers containing hydroquinonyl developingradicals diffuse from the negative to the positive as the sodium orother alkali salt. The diffusion rate of such dye imageformingcomponents thus is at least partly a function of the alkaliconcentration, and it is necessary that the pH of the image layer remainon the order of, for example, 12 to 14 until transfer of the necessaryquantity of dye has been accomplished. The subsequent pH reduction, inaddition to its desirable effect upon image light stability, serves ahighly valuable photographic function by substantially terminatingfurther dye transfer.

In order to prevent premature pH reduction during transfer processing,as evidenced, for example, by an undesired reduction in positive imagedensity, the acid groups are disclosed to be so distributed in the acidpolymer layer that the rate of their availability to the alkali iscontrollable, e.g., as a function of the rate of swelling of the polymerlayer which rate in turn has a direct relationship to the diffusion rateof the alkali ions. The desired distribution of the acid groups in theacid polymer layer may be effected by mixing the acid polymer with apolymer free of acid groups, or lower in concentration of acid groups,and compatible therewith, or by using only the acid polymer butselecting one having a relatively lower proportion of acid groups. Theseembodiments are illustrated, respectively, in the cited copendingapplication, by (a) a mixture of cellulose acetate and cellulose acetatehydrogen phthalate and (b) a cellulose acetate hydrogen phthalatepolymer having a much lower percentage of phthalyl groups than thefirst-mentioned cellulose acetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acidmay contain a water-insoluble polymer, preferably a cellulose ester,which acts to control or modulate the rate at which the alkali salt ofthe polymer acid is formed. As examples of cellulose esters contemplatedfor use, mention is made of cellulose acetate, cellulose acetatebutyrate, etc. The particular polymers and combinations of polymersemployed in any given embodiment are, of course, selected so as to haveadequate wet and dry strength and when necessary or desirable, suitablesubcoats are employed to help the various polymeric layers adhere toeach other during storage and use.

The inert spacer layer of the last-mentioned patent, for example, aninert spacer layer comprising polyvinyl alcohol or gelatin, acts to timecontrol the pH reduction by the polymeric acid layer. This timing isdisclosed to be a function of the rate at which the alkali diffusesthrough the inert spacer layer. It is there stated to have been foundthat the pH does not drop until the alkali has passed through the spacerlayer, i.e., the pH is not reduced to any significant extent by the merediffusion into the interlayer, but the pH drops quite rapidly once thealkali diffuses through the spacer layer.

It has now been quite unexpectedly discovered that the problems inherentin fabricating a film unit of the type where the image-receivingelement, the alkali processing composition and the photosensitiveelement are maintained in contiguous contact during processing andsubsequent to dye transfer image formation, for example, a film unit ofthe type described, with reference to aforementioned U.S. Pat. No.2,983,606, may be effectively obviated in a considerably simplifiedmanner by fabrication of a film unit in accordance with the physicalparameters detailed below.

Specifically, it has been quite unexpectedly discovered that an integralphotographic film unit of simplified construction and particularlyadapted for the production of dye transfer images of unexpectedlyimproved stability and other desirable properties by a color diffusiontransfer process will be constructed to include a photosensitive elementcomprising a composite structure possessing, in sequence, as essentiallayers, a first dimensionally stable layer, a photosensitive silverhalide emulsion layer having associated therewith a dye image-formingmaterial which is soluble and diffusible at a first processingcomposition solvent concentration, a polymeric layer dyeable by the dyeimage-forming material, and a second dimensionally stable layertransparent to incident actinic radiation, wherein the dimensionallystable layers taken together, possess a processing composition solventvapor perme' ability sufficient to effect, subsequent to substantial dyetransfer image formation and preceding substantial dye transfer imagedegradation, osmotic transpiration of processing composition solvent ina quantity effective to decrease the first solvent concentration, atwhich the dye image-forming material is soluble and diffusible, to asecond solvent concentration, at which the dye image-forming material issubstantially non'diffusible. In combination with the compositestructure, a rupturable container retaining a processing compositioncomprising the solvent is fixedly positioned and extends transverse aleading edge of the composition structure whereby to effect, uponapplication of compressive pressure, discharge of the processingcomposition intermediate the dyeable polymeric layer and thephotosensitive silver halide emulsion next adjacent, in a quantitysufficient to provide the first solvent concentration. Although bothdimensionally stable layers may be transparent and in such instance, anopacifying agent may be initially dispersed intermediate the dyeablepolymeric layer and the next adjacent silver halide emulsion layer, in aquantity sufiicient to mask the dye image-forming material, suchopacifying agent will preferbaly be disposed within the processingcomposition, in a quantity sufficient to mask the dye image-formingmaterial upon distribution of the processing composition intermediatethe last stated layers, and, most preferably, the dimensionally stablelayer next adjacent the photosensitive silver halide emulsion layer willbe opaque with respect to externally derived incident actinic radiation.

In view of the fact that the preferred dye imageproviding materialscomprise dyes which are silver halide developing agents, as statedabove, for purposes of simplicity and clarity, the present inventionwill be further described hereinafter in terms of such dyes, withoutlimitation of the invention to the illustrative dyes denoted, and, inaddition, the photographic film unit structure will be detailedhereinafter employing the last-mentioned preferred structuralembodiment, without limitation of the invention to the preferredstructure denoted.

Although in point of fact, the dimensionally stable layers employed inthe practice of the present invention may employ dimensionally stablelayers which possess a vapor transmission rate of 1 or less gms./24hrs./ 100 in. /mil, in a preferred embodiment of the present inven tion,the layers employed will posses a vapor transmission rate for theselected processing composition solvent averaging not less than about100 gm's./ 24 hrs./ 100 in. /rnil, most preferably in terms of thepreferred solvent, water, a vapor transmission rate averaging in excessof about 300 gms. of water/24 hrs/100 in. /mil, and may advantageouslycomprise a microporous polymeric film possessing a pore distributionwhich does not unduly interfere with the dimensional stability of thelayers or, where required, the optical characteristics of such layers.Such pore distribution may comprise, for example, an average porediameter of from less than about microns to greater than about 100microns and a pore volume of less than about 3% to greater than about7%.

In a particularly preferred embodiment of the present invention, thepreferred solvent, water, may be employed in a weight/weight ratio ofabout 1:10 to 1:20 dye to water at a ratio of about 1:3 to 1:10 liquidpermeable polymer to water and most preferably will be fabricated tocomprise about 300 to 1300 mgs./ft. liquid permeable polymeric bindermaterial, about 200 to 400 mgs./ft. dye and about 5000 mgs./ft. water.

The dimensionally stable layers are designed so that there is no liquidflow through the layers while allowing the vapor of the processingcomposition solvent to pass by diffusion from the evaporating liquidbody and the operational efiiciency of the film unit is directlydependent upon the nature and quality of the vapor permeable membranecharacteristics of the layers selected. The vapor transmissioncharacteristics desired are directed to maximization of the rate atwhich the required quantity of processing solvent is effectivelyevacuated from the film unit subsequent to substantial dye transferimage formation by diffusion transfer processing, commensurate withmaintaining the liquid impermeability and dimensional stabilitycharacteristics of the layers. Thus, the layers should possess themaximum vapor transmission capacity which permits the passage ofprocessing composition solvent vapor, and any gas dissolved therein, atits vapor pressure, without allowing passage of fluid processingcomposition. The layers employed in accordance with the presentinvention therefor should be as thin as possible for solvent vaportransmission efliciency yet retain sufficient strength to providestability to and resist chemical and physical degradation of the filmunit under conditions of use.

In a preferred embodiment of the present invention, the film unit isspecifically adapted to provide for the production of a multicolor dyetransfer image and the photosensitive laminate comprises, in order ofessential layers, the dimensionally stable opaque layer; at least twoselectively sensitized silver halide emulsion strata each having dyeimage-providing materials of predetermined color associated therewithwhich are soluble and diffusible, in alkali, at a first processingcomposition solvent concentration; an alkaline solution permeablepolymeric layer dyeable by the dye image-providing materials; and thedimensionally stable transparent layer.

The silver halide emulsions comprising the multicolor photosensitivelaminate preferably possess predominant spectral sensitivity to separateregions of the spectrum and each has associated therewith a dye, whichis a silver halide developing agent and is, most preferably,substantially soluble in the reduced form only at the first solventconcentration possessing subsequent to processing a spectral absorptionrange substantially complementary to the predominant sensitivity rangeof its associated emulsion.

In the preferred embodiment, each of the emulsion strata, and itsassociated dye, is separated from the remaining emulsion strata, andtheir associated dye, by separating alkaline solution permeablepolymeric interlayers.

In such preferred embodiment of the invention, the silver halideemulsion comprises photosensitive silver halide dispersed in gelatin andis about 0.6 to 6 microns in thickness; the dye itself is dispersed inan aqueous alkaline solution polymeric binder, preferably gelatin, as aseparate layer about 1 to 7 microns in thickness; the alkaline solutionpermeable polymeric interlayers, preferably gelatin, are about 1 to 5microns in thickness; the alkaline solution dyeable polymeric layer istransparent and about 0.25 to 0.4 mil in thickness; and each of thedimensionally stable opaque and transparent layers are alkaline solutionimpermeable, processing composition vapor permeable and about 2 to 6mils, in thickness. It will be specifically recognized that the relativedimensions recited above may be appropriately modified, in accordancewith the desires of the operator, with respect to the specific productto be ultimately prepared.

In the preferred embodiment of the present inventions film unit for theproduction of a multicolor transfer image, the respective silverhalide/dye developer units of the photosensitive element will be in theform of a tripack configuration which will ordinarily comprise a cyandye developer/red-sensitive emulsion unit contiguous the dimensionallystable opaque layer, the yellow dye developer/blue-sensitive emulsionunit most distant from the opaque layer and the magenta dyedeveloper/greensensitive emulsion unit intermediate those units,recognizing that the relative order of such units may be varied inaccordance with the desires of the operator.

Employment of the detailed film unit of the present invention, accordingto the hereinafter described color diffusion transfer process,specifically provides for the production of a highly stable transferimage accomplished, at least in part, by effectively obviating thepreviously discussed disadvantages of the prior art products andprocesses, by in process adjustment of the environmental processingcomposition solvent concentration from a solvent concentration at whichdye diffusion or transfer is operative to a solvent concentration atwhich dye transfer is inoperative subsequent to substantial transferimage formation. The stable color transfer image is obtainedirrespective of the fact that the film unit is maintained as an integrallaminate unit during exposure, processing, viewing, and storage of theunit. Accordingly, by means of the present invention, multicolortransfer images may be provided over an extended processing temperaturerange which exhibit desired maximum and minimum dye transfer imagedensities; yellow, magenta and cyan dye saturation; red, green and bluehues; and color separation. These unexpected advantages are in additionto the manufacturing advantages obtained by reason of the presentinventions integral color transfer film unit and which will be readilyapparent from examination of the units parameters, that is, for example,advantages in more efiicient utilization of fabricating materials andcomponents, en hanced simplicity of film manufacture and camera designand construction, and more simplified and effectively controlledcustomer utilization of the unit.

Reference is now made to FIGS. 1 through 7 of the drawings wherein thereis illustrated a preferred film unit of the present invention andwherein like numbers, appearing in the various figures, refer to likecomponents.

As illustrated in the drawings, FIG. 1 sets forth a perspective view ofthe film unit, designated 10, and each of FIGS. 2. through 7 illustratediagrammatic cross-sectional views of film unit 10, along the statedsection lines 22, 3-3, 55, and 77, during the various depicted stages inthe performance of a photographic diffusion transfer process as detailedhereinafter.

Film unit .10 comprises rupturable container 11, retaining, prior toprocessing, aqueous alkaline solution 12, and photosensitive laminate 13including, in order, dimensionally stable opaque layer 14, preferably anactinic radiation-opaque flexible sheet material; cyan dye developerlayer 15; red-sensitive silver halide emulsion layer 16; interlayer 17;magenta dye developer layer 18; green-sensitive silver halide emulsionlayer 19; interlayer 20; yellow dye developed layer 21; blue-sensitivesilver halide emulsion layer 22; auxiliary layer 23, which may containan auxiliary silver halide developing agent; image-receiving layer 24;and dimensionally stable transparent layer 27, preferably an actinicradiation transmissive flexible sheet material.

The structural integrity of laminate 13 may be maintained, at least inpart, by the adhesive capacity exhibited between the various layerscomprising the laminate at their opposed surfaces. However, the adhesivecapacity exhibited at an interface intermediate image-receiving layer 24and the silver halide emulsion layer next adjacent thereto, for example,intermediate image-receiving layer 24 and auxiliary layer 23 asillustrated in FIGS. 2 through 7, should be less than that exhibited atthe interface between the opposed surfaces of the remainder of thelayers forming the laminate, in order to facilitate distribution ofprocessing solution 12 intermediate the stated imagereceiving layer 24and the silver halide emulsion layer next adjacent thereto. Thelaminates structural integrity may also be enhanced or provided, inwhole or in part, by providing a binding member extending around, forexample, the edges of laminate 13, and maintaining the layers comprisingthe laminate intact, except at the interface between layers 23 and 24during distribution of alkaline solution 12 intermediate those layers.As illustrated in the figures, the binding member may comprise apressure-sensitive tape 28 securing and or maintaining the layers oflaminate 13 together at its respective edges. Tape 28 will also act tomaintain processing solution 12 intermediate image-receiving layer 24and the silver halide emulsion layer next adjacent thereto, uponapplication of compressive pressure to pod 11 and distribution of itscontents intermediate the stated layers. Under such circumstances,binder tape 28 will act to prevent leakage of fluid processingcomposition from the film units laminate during and subsequent tophotographic processing.

Rupturable container 11 may be of the type shown and described in any ofU.S. Pats. Nos. 2,543,181; 2,634,- 886; 2,653,732; 2,723,051; 3,056,492;3,056,491; 3,152,- 515; and the like. In general, such containers willcomprise a rectangular blank of fluidand air-impervious sheet materialfolded longitudinally upon itself to form two Walls 29 which are sealedto one another along their longitudinal and end margins to form a cavityin which processing solution 12 is retained. The longitudinal marginalseal 30 is made weaker than the end seals 31 so as to become unsealed inresponse to the hydraulic pressure generated within the fluid contents12 of the container by the application of compressive pressure to walls29 of the container.

As illustrated in FIGS. 1, 2 and 4, container 11 is fixedly positionedand extends transverse a leading edge of photosensitive laminate 13whereby to effect unidirectional discharge of the containers contents 12between image-receiving layer 24 and the stated layer next adjacentthereto, upon application of compressive force to container 11. Thus,container 11, as illustrated in FIG. 2, is fixedly positioned andextends transverse a leading edge of laminate 13 with its longitudinalmarginal seal 30 directed toward the interface between image-receivinglayer 24 and auxiliary layer 23. As shown in FIGS. 1, 2

and 4, container 11 is fixedly secured to laminate 13 by extension 32 oftape 28 extending over a portion of one wall 29 of the container, incombination with a separate retaining member such as illustratedretaining tape 33 extending over a portion of the other wall 29 of thecontainer and a portion of laminate 13s surface generally equal in areato about that covered by tape 28.

As illustrated in FIG. 6, extension flap 32 of tape 28 is preferably ofsuch area and dimensions that upon, for example, manual separation ofcontainer 11 and tape 33, subsequent to distribution of processingcomposition 12, from the remainder of film unit 10, flap 32 may befolded over the edge of laminate 13, previously covered by tape 33, inorder to facilitate maintenance of the laminates structural integrity,for example, during the flexations inevitable in storage and use of theprocessed film unit, and to provide a suitable mask or frame, forviewing of the transfer image through the picture viewing area of transparent layer 27.

The fluid contents of the container comprise an aqueous alkalinesolution having a pH and solvent concentration at which the dyedevelopers are soluble and dilfusible and contains an opacifying agentin a quantity sufficient to mask the dye developers associated with thesilver halide emulsions subsequent to processing. In general, in apreferred embodiment the concentration of opacifying agent or agentsselected will be that suflicient to prevent further exposure of the filmunits silver halide emulsion or emulsions, by actinic radiationtraversing through the dimensionally stable transparent layer,subsequent to distribution of the processing solution intermediate thedyeable polymeric layer and the stated layer next adjacent thereto.Accordingly, the film unit may be processed, subsequent to distributionof the composition, in the presence of such radiation, in view of thefact that the silver halide emulsion or emulsions or the laminate areappropriately protected by incident radiation, at one major surface bythe opaque processing composition and at the remaining major surface bythe dimensionally stable opaque layer. If the illustrated binder tapesare also opaque, edge leakage of actinic radiation incident on theemulsion or emulsions will also be prevented. The selected opacifyingagent, however, should be one providing a background suitable forviewing the dye developer transfer image formed in the dyeable polymericlayer. In general, while substantially any opacifying agent may beemployed, it is preferred that an opacifying agent be selected that willnot interfere with the color integrity of the dye transfer image, asviewed by the observer, and, most preferably, an agent which isaesthetically pleasing to the viewer and does not provide a backgroundnoise signal degrading, or detracting from, the information content ofthe image. Particularly desirable opacifying agents will be thoseproviding a white background, for viewing the transfer image, andspecifically those conventionally employed to provide background forreflection photographic prints and, especially, those agents possessingthe optical properties desired for reflection of incident radiation.

As examples of opacifying agents, mention may be made of barium sulfate,zinc oxide, titanium oxide, barium stearate, silver flake, silicates,alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconiumsulfate, kaolin, mica, and the like.

A particularly preferred agent comprises titanium dioxide due to itshighly effective reflection properties. In general, based upon percenttitanium dioxide (weight volume), a processing composition containingabout 40 70 grams of titanium dioxide dispersed in 100 cc. of water willprovide a percent reflectance of about -90% In the most preferredembodiments, the percent reflectance particularly desired will be in theorder of above 85%.

Where it is desired to increase the radiation filtering capacity of aprocessing composition containing, for example, titanium dioxide or thelike, selected predominantly for its radiation reflecting properties,beyond that ordinarily obtained or required to obscure or mask the dyeand/or developed silver associated with the Photosensitive silver halideemulsion layers, it may also be desirable to provide an additionalopacifying agent, exhibiting more effective filtration of radiationincident on the transparent support layer during processing, such ascarbon black, for example, added in a concentration of about one partcarbon black to 100 to 500 parts titanium dioxide, in order to furtherprotect the emulsions from physical fog formation during processing.

In the performance of a diffusion transfer multicolor process employingfilm unit 10, the unit is exposed to radiation, actinic tophotosensitive laminate 13, incident on the laminates exposure surface34, as illustrated in FIG. 2.

Subsequent to exposure, as illustrated by FIGS. 2 and 4, film unit isprocessed by being passed through opposed suitably gapped rolls 35 inorder to apply compressive pressure to frangible container 11 and toeffect rupture of longitudinal seal 30 and distribution of alkalineprocessing composition 12, having a pH and solvent concentration atwhich the cyan, magenta and yellow dye developers are soluble anddilfusible, intermediate dyeable polymeric layer 24 and auxiliary layer23.

Alkaline processing solution 12 permeates emulsion layers 16, 19 and 22to initiate development of the latent images contained in the respectiveemulsions. The cyan, magenta and yellow dye developers, of layers 15, 18and 21, are immobilized, as a function of the development of theirrespective associated silver halide emulsions, preferably substantiallyas a result of their conversion from the reduced form to theirrelatively insoluble and nondiffusible oxidized form, thereby providingimagewise distributions of mobile, soluble and dilfusible cyan, magentaand yellow dye developer, as a function of the point-to-point degree oftheir associated emulsions exposure. At least part of the imagewisedistributions of mobile cyan, magenta and yellow dye developertransfers, by diffusion, to aqueous alkaline solution permeablepolymeric layer 24 to provide a multicolor dye transfer image to thatlayer. Subsequent to substantial transfer image formation, a sufiicientportion of the solvent comprising aqueous alkaline solution 12transfers, by osmotic diffusion, through vapor permeable, liquidimpermeable polymeric layers 14 and 27 whereby alkaline solution 12decreases in solvent concentration, as a function of diffusion, to asolvent concentration at which the cyan, magenta and yellow dyedevelopers, in the reduced form, are nondiffusible, to provide thereby astable multicolor dye transfer image.

Subsequent to distribution of processing solution 12, container 11 maybe manually dissociated from the remainder of the film unit, asdescribed above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed inconjunction with the following specific examples which set outrepresentative embodiments and photographic utilization of the novelphotographic film units of this invention, which, however, are notlimited to the details therein set forth and are intended to beillustrative only.

Film units similar to that shown in the drawings may be prepared, forexample, by coating, in succession, on a gelatin subbed, 5 mil opaquecellulose triacetate film base possessing a water vapor permeability of324 grams of water/ 24 hrs/100 inF/mil, the following layers;

(1) A layer of the cyan dye developer1,4-bis-(B-[hydroquinonyl-a-methyl]-ethylamino) 5,8dihydroxyanthraquinone dispersed in gelatin and coated at a coverage ofabout 150 mgs./ft. of dye and about 200 mgs./ft. of gelatin;

(2) A red-sensitive gelatinosilver iodobromide emulsion coated at acoverage of about 200 mgs./ft. of silver and about mgs./ft. of gelatin;

(3) A layer of gelatin coated at a coverage of about 200 mgs./ft.

(4) A layer of the magenta dye developer Z-(p-[flhydroquinonylethyl]phenylazo)-4-isopropoxy-lnaphthol dispersed in gelatin and coated at acoverage of 70 tngs./ ft. of dye and about 100 mgs./ft. of gelatin;

(5) A green-sensitive gelatino-silver iodobromide emulsion coated at acoverage of about 100 tugs/ft. of silver and 60 rugs/ft. of gelatin;

(6) A layer containing 4-methylphenyl hydroquinone dispersed in gelatinand coated at a coverage of about 25 mgs./ft. of 4'-methylphenylhydroquinone and about mgs./ft. of gelatin;

(7) A layer of the yellow dye developer4-(p-[fl-hydroquinonylethyl]-phenylazo) 3(N-n-hexylcarboxamido)-1-phenyl-5-pyrazolone dispersed in gelatin andcoated at a coverage of about 40 mgs./ft. of dye and 50 mgs./ft. ofgelatin;

(8) A blue-sensitive gela-tino-silver iodobromide emulsion coated at acoverage of about 60 mgs./ft. of silver and about 50 mgs./ft. ofgelatin; and

(9) A layer of gelatin coated at a coverage of about 30 mgs./ft. ofgelatin.

Then a transparent 5 mil cellulose triacetate film base possessing awater vapor permeability of 324 grams of water/24 hrs/100 in. /mil maybe coated with a 2:1 mixture, by weight, of polyvinyl alcohol andpoly-4-vinylpyridine, at a coverage of approximately 600 mgs./ft. toprovide a polymeric image-receiving layer approximately 0.40 mil thick.

The two components thus prepared may then be taped together in laminateform, at their respective edges, by

means of a pressure-sensitive binding tape extending around, in contactwith, and over the edges of the resultant laminate.

A rupturable container comprising an outer layer of lead foil and aninner liner or layer of polyvinyl chloride retaining an aqueous alkalineprocessing solution comprising:

,- Water cc 100 Potassium hydroxide grams 11.2 Hydroxyethyl cellulose(high viscosity) [commercially available from Hercules Powder Co.,

Wilmington, Delaware, under the trade name Natrasol 250] grams 3.4N-benzyl-ot-picolinium bromide grams 1.5 Titanium dioxide grams 40.0Benzotriazole grams 1.0

may then be fixedly mounted on the leading edge, of each of thelaminates, by pressure-sensitive tapes interconnecting the respectivecontainers and laminates, such that upon application of compressivepressure to a container its contents would be distributed, upon ruptureof the containers marginal seal, between layer 9 and the polymericimage-receiving layer.

The photosensitive laminates may then be exposed through step wedges toselectively filtered radiation incident on the transparent cellulosetriacetate layer and initially processed, in the absence of actinicradiation, by passage of the exposed film unit through suitably gappedopposed rolls, to effect rupture of the container and distribution ofits contents. During processing, the multicolor dye transfer imageformation may be viewed through the transparent cellulose triacetatefilm base and such image formation is found to be substantiallycompleted and exhibiting the required color brilliance, hues,saturation, stability and isolation, within a period of approximatelyninety seconds.

Particularly desirable film units of the last-described type may also beadvantageously fabricated employing microporous film base materials insubstitution for the identified cellulose triacetate materials. Forexample, film units may be fabricated employing 2 and 4 mil polyethyleneterephthalate film base possessing an average pore diameter of about 23to 107 microns and a pore volume of about 3 to 7%.

The pH and solvent concentration of the alkaline processing solutioninitially employed must be an alkaline pH at which the dye developersemployed are soluble and diffusible. Although it has been found that thespecific pH to be employed may be readily determined empirically for anydye developer, or group of dye developers, most particularly desirabledye developers are soluble at pHs above 9 and relatively insoluble atpHs below 9, in reduced form, and relatively insoluble at substantiallyany alkaline pH, in oxidized form, and the system can be readilybalanced accordingly for such dye developers. In addition, although aspreviously noted, the processing composition, in the preferredembodiment, will include the stated film-forming viscosity-increasingagent, or agents, to facilitate spreading of the composition and toprovide maintenance of the spread composition as a structurally stablelayer of the laminate, subsequent to distribution, it is not necessarythat such agent be employed as a component of the composition.

Where desired, a polymeric acid layer, for example, of the typediscussed above, may be additionally incorporated, as stated, in thefilm unit of the present invention, to provide reduction of thealkalinity of the processing solution from a pH at which the dyes aresoluble to a pH at which the dyes are substantially nondifiusible, inorder to advantageously further stabilize the dye transfer image. Insuch instance, the polymeric acid layer may be positioned intermediatethe transparent support and image-receiving layer, and/or the opaquesupport and next adjacent emulsion/dye unit layer, and the film unit mayalso contain a polymeric spacer or barrier layer next adjacent thepolymeric acid layer, opposite the respective support layer, aspreviously described.

The dimensionally stable support layers referred to may comprise any ofthe various types of conventional opaque and transparent rigid orflexible materials possessing the requisite liquid impermeability andvapor transmissivity denoted above, and may comprise polymeric films ofboth synthetic types and those derived from naturally occurringproducts. Particularly suitable materials include aqueous alkalinesolution impermeable, Water vapor permeable, flexible polymericmaterials such as vapor permeable polymeric films derived from ethyleneglycol terephthalic acid, vinyl chloride polymers; polyvinyl acetate;polyamides; polymethacrylic acid methyl and ethyl esters; cellulosederivatives such as cellulose, acetate, triacetate, nitrate, propionate,butyrate, acetatepropionate, or acetate-butyrate; alkaline solutionimpermeable, water vapor permeable papers; crosslinked polyvinylalcohol; regenerated cellulose; and the like.

It will be noted that the liquid processing composition employed maycontain an auxiliary or accelerating developing agent, such asp-methylaminophenol, 2,4-diaminophenol, p-benzylaminophenyl,hydroquinone, toluhydroquinone, phenylhydroquinone, 4'methylphenylhydroquinone, etc. It is also contemplated to employ aplurality of auxiliary or accelerating developing agents, such as a3-pyrazolidone developing agent and a benzenoid developing agent, asdisclosed in U.S. Pat. No. 3,039,- 869, issued June 19, 1962. Asexamples of suitable combinations of auxiliary developing agents,mention may be made of 1-phenyl-3-pyrazolidone in combination withpbenzylaminophenol and l-phenyl 3 pyrazolidone in combination with 2,5bis ethylenimino-hydroquinone. Such auxiliary developing agents may beemployed in the liquid processing composition or they may be initiallyincorporated, at least in part, in any one or more of the silver halideemulsion strata, the strata containing the dye developers, theinterlayers, the overcoat layer, the image-receiving layer, or in anyother auxiliary layer, or layers, of the film unit. It may be noted thatat least a portion of the dye developer oxidized during development maybe oxidized and immobilized as a result of a reaction, e.g., anenergy-transfer reaction, with the oxidation product of an oxidizedauxiliary developing agent, the latter developing agent being oxidizedby the development of exposed silver halide. Such a reaction of oxidizeddeveloping agent with unoxidized dye developer would regenerate theauxiliary developing agent for further reaction with the exposed silverhalide.

In addition, development may be effected in the presence of an oniumcompound, particularly a quaternary ammonium compound, in accordancewith the processes disclosed in U.S. Pat. No. 3,173,786, issued Mar. 16,1965.

It will be apparent that the relative proportions of the agents of thediffusion transfer processing composition may be altered to suit therequirements of the operator. Thus, it is within the scope of thisinvention to modify the herein described developing compositions by thesubstitution of preservatives, alkalies, etc., other than thosespecifically mentioned, provided that the pH of the composition isinitially at the first pH and solvent concentration required. Whendesirable, it is also contemplated to include, in the developingcomposition, components such as restrainers, accelerators, etc.Similarly, the concentration of various components may be varied over a.wide range and when desirable adaptable components may be disposed inthe photosensitive element, prior to exposure, in a separate permeablelayer of the photosensitive element and/or in the photosensitiveemulsion.

In all examples of this specification, percentages of components aregiven by weight unless otherwise indicated.

An extensive compilation of specific dye developers particularly adaptedfor employment in photographic diffusion transfer processes is set forthin aforementioned U.S. Pat. No. 2,983,606 and in the various copendingU.S. applications referred to in that patent, especially in the table ofU.S. applications incorporated by reference into the patent as detailedin column 27. As examples of additional U.S. patents detailing specificdye developers for photographic transfer process use, mention may alsobe made of U.S. Pats. Nos. 2,983,605; 2,992,- 106; 3,047,386; 3,076,808;3,076,820; 3,077,402; 3,126,- 280; 3,131,061; 3,134,762; 3,134,765;3,135,604; 3,135,- 605; 3,135,606; 3,135,734; 3,141,772; 3,142,565; andthe like.

As additional examples of synthetic, film-forming, permeable polymersparticularly adapted to retain dispersed dye developer, mention may bemade of nitrocarboxymethyl cellulose, as disclosed in U.S. Pat. No.2,992,104; an acylamidobenzene sulfo ester of a partial sulfobenzal ofpolyvinyl alcohol, as disclosed in U.S. Pat. No. 3,043,- 692; polymersof N-alkyl-a,/3-unsaturated carboxamides and copolymers ofNalkyl-a,,8-carboxamides with N-hydroxyalkyl-a,/3-unsaturatedcarboxamides, as disclosed in U.S. Pat. No. 3,069,263; copolymers ofvinylphthalimide and c p-unsaturated carboxylic acids, as disclosed inU.S. Pat. No. 3,061,428; copolymers of N-vinylpyrrolidones and cp-unsaturated carboxylic acids and terepolymers of N-vinylpyrrolidones,n p-unsaturated carboxylic acids and alkyl esters of a,/3-unsaturatedcarboxylic acids, as disclosed in U.S. Pat. No. 3,044,873; copolymers ofN,N-dialkyl-ot,B-unsaturated carboxamides -with u,,8-unsaturatedcarboxylic acids, the corresponding amides of such acids, and copolymersof N-aryl-and N- cyclo-alkyl-ut,fi-unsaturated carboxamides witha,{3-unsaturated carboxylic acids, as disclosed in U.S. Pat. No.3,069,264; and the like.

In addition to conventional techniques for the direct dispersion of aparticulate solid material in a polymeric,

or colloidal, matrix such as ball-milling and the like techniques, thepreparation of the dye developer dispersion may also be obtained bydissolving the dye in an appropriate solvent, or mixture of solvents,and the resultant solution distributed in the polymeric binder, withoptional subsequent removal of the solvent, or solvents, employed, as,for example, by vaporization where the selected solvent, or solvents,possesses a sufficiently loW boiling point or washing where the selectedsolvent, or solvents, possesses a sufficiently high differentialsolubility in the wash medium, for example, water, when measured againstthe solubility of the remaining composition components, and/or obtainedby dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of thetypes referred to above, and for an extensive compilation of theconventional solvents tradi tionally employed in the art to effectdistribution of photographic color-providing materials in polymericbinders, specifically for the formation component layers of photographicfilm units, reference may be made to U.S. Pats. Nos. 2,269,158;2,322,027; 2,304,939; 2,304,940; 2,801,- 171; and the like.

Although the invention has been discussed in detail throughout employingdye developers, the preferred dye image-providing materials, it will bereadily recognized that other, less preferred, dye image-providingmaterials may be substituted in replacement of the preferred dyedevelopers in the practice of the invention. For example, there may beemployed dye image-forming materials such as those disclosed in U.S.Pats. Nos. 2,647,049, issued July 28, 1953; 2,661,293, issued Dec. 1,1953; 2,698,244, issued Dec. 28, 1954; 2,698,798, issued Jan. 4, 1955;and 2,802,735, issued Aug. 13, 1957, wherein color diffusion transferprocesses are described which employ color coupling techniquescomprising, at least in part, reacting one or more color developingagents and one or more color formers or couplers to provide a dyetransfer image to a superposed image-receiving layer and those disclosedin U.S. Pat. 2,774,668, issued Dec. 18, 1956, wherein color diffusiontransfer processes are described which employ the imagewise differentialtransfer of complete dyes by the mechanisms therein described to providea transfer dye image to a contiguous image-receiving layer.

For the production of photosensitive gelatino silver halide emulsionsemployed to provide the film unit, the silver halide crystals may beprepared by reacting a water soluble silver salt, such as silvernitrate, with at least one Water-soluble halide, such as ammonium,potassium or sodium bromide, preferably together with a correspondingiodide, in an aqueous solution of a peptizing agent such as a colloidalgelatin solution; digesting the dispersion at an elevated temperature,to provide increased crystal growth; washing the resultant dispersion toremove undesirable reaction products and residual water-soluble salts bychilling the dispersion, noodling the set dispersion, and washing thenoodles with cold water, or alternatively, employing any of the variousfiocc systems, or procedures, adapted to effect removal of undesiredcomponents, for example, the procedures described in U.S. Pats. Nos.2,614,928; 2,614,929; 2,728,662; and the like; after-ripening thedispersion at an elevated temperature in combination with the additionof gelatin and various adjuncts, for example, chemical sensitizingagents of U.S. Pats. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856;2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all accordingto the traditional procedures of the art, as described in Neblette, C.B., Photography, Its Materials and Processes, 6th ed., 1962.

Optical sensitization of the emulsions silver halide crystals may beaccomplished by contact of the emulsion composition with an effectiveconcentration of the selected optical sensitizing dyes dissolved in anappropriate dispersing solvent such as methanol, ethanol, acetone,water, and the like; all according to the traditional procedures of theart, as described in Hammer, F. M., The Cyanine Dyes and RelatedCompounds.

Additional optional additives, such as coating aids, hardeners,viscosity-increasing agents, stabilizers, preservatives, and the like,for example, those set forth hereinafter, also may be incorporated inthe emulsion formulation, according to the conventional procedures knownin the photographic emulsion manufacturing art.

The photoresponsive material of the photographic emulsion will, aspreviously described, preferably comprise a crystal of silver, forexample, one or more of the silver halides such as silver chloride,silver iodide, silver bromide, or mixed silver halides such as silverchlorobromide or silver iodobromide, of varying halide ratios andvarying silver concentrations.

The emulsions may include the various adjuncts, or addenda, according tothe techniques disclosed in the art, such as speed-increasing compoundsof the quaternary ammonium type, as described in U.S. Pats. Nos.2,271,623; 2,288,226; and 2,334,864; or of the polyethyleneglycol type,as described in U.S. Pat. No.,2,708,162; or the preceding combination,as described in U.S. Pat. No. 2,886; 437; or the thiopolymers, asdescribed in U.S. Pats. Nos. 3,046,129 and 3,046,134.

The emulsions may also be stabilized with the salts of noble metals suchas ruthenium, rhodium, palladium, iridium and platinum, as described inU.S. Pats. Nos. 2,566,245 and 2,566,263; and the mercury compounds ofU.S. Pats. Nos. 2,728,663; 2,728,664 and 2,728,665; the triazoles ofU.S. Pat. No. 2,444,608; the azindines of U.S. Pats. Nos. 2,444,605;2,444,606; 2,444,607; 2,450,397; 2,444,609; 2,713,541; 2,743,181;2,716,062; 2,735,769; 2,756,147; 2,772,164; and those disclosed by Burrin Zwiss. Pot., volume 47, 1952, pages 228; the disulfides of BelgianPat. No. 569,317; the benzothiazolium compounds of U.S. Pats. Nos.2,131,038 and 2,694,716; the zinc and cadmium salts of U.S. Pat. No.2,839,405; and the mercapto compounds of U.S. Pat. No. 2,819,965.

Hardening agents such as inorganic agents providing polyvalent metallicatoms, specifically polyvalent alumi num or chromium ions, for example,potash alum and chrome alum [K Cr (SO -24H O] and inorganic agents ofthe aldehyde type, such as formaldehyde, glyoxal, mucochloric, etc.; theketone type such as diacetyl; the quinone type; and the specific agentsdescribed in U.S. Pats. Nos. 2,080,019; 2,725,294; 2,725,295; 2,725,305;2,726,162; 2,732,316; 2,950,197; and 2,870,013, may be incorporated,where desired and compatible, in the selected coating solutioncompositions.

Coating solution compositions employed to fabricate the respectivestrata of the film unit may contain one or more coating aids, wheredesired and compatible, such as saponin; a polyethyleneglycol of U.S.Pat. No. 2,831,766; a polyethyleneglycol ether of U.S Pat. No.2,719,087, a taurine of U.S. Pat. No. 2,739,891; a maleopimarate of U.S.Pat. No. 2,823,123; and amino acid of U.S. Pat. No. 3,038,804; asulfosuccinamate of U.S. Pat. No. 2,922,108; or a polyether of U.S. Pat.No. 2,600,831; or a gelatin plasticizer such as glycerin; adihydroxyalkane of U.S. Pat. No. 2,960,404; a bis-glycolic acid ester ofU.S. Pat. No. 2,904,434; a succinate of U.S. Pat. No. 2,940,854; or apolymeric hydrosol of U.S. Pat. No. 2,852,386.

As the binder for the respective emulsion strata, the aforementionedgelatin may be, in whole or in part, replaced with some other colloidalmaterial such as albumin; casein; or zein; or resins such as a cellulosederivative, as described in U.S. Pats. Nos. 2,322,085 and 2,327,808;polyacrylamides, as described in U.S. Pat. No. 2,541,474; vinyl polymerssuch as described in U.S. Pats. Nos. 2,253,078; 2,276,322; 2,276,323;2,281,703; 2,310,223; 2,311,058; 2,311,059; 2,414,208; 2,461,023;2,484,456; 2,538,257; 2,579,016; 2,614,931; 2,624,674; 2,632,704;

and the like.

Although the preceding description of the invention has been couched interms of the preferred photosensitive component construction wherein atleast two selectively sensitized photosensitive strata are in contiguouscoplanar relationship and, specifically, in terms of the preferredtripack type structure comprising a red-sensitive silver halide emulsionstratum, a green-sensitive silver halide emulsion stratume and ablue-sensitive silver halide emulsion stratum having associatedtherewith, respectively, a cyan dye developer, a magenta dye developerand a yellow dye developer, the photosensitive components of the filmunit may comprise at least two sets of selectively sensitized minutephotosensitive elements arranged in the form of a photosensitive screenwherein each of the minute photosensitive elements has associatedtherewith, for example, an appropriate dye developer in or behind itsrespective silver halide emulsion portion. In general, a suitablephotosensitive screen will comprise minute red-sensitized emulsionelements, minute green-sensitized emulsion elements and minuteblue-sensitized emulsion elements arranged in side-by-side relationshipin a screen pattern and having associated therewith, respectively, acyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dyedeveloper and the use of a mixture of dye developers adapted to providea black and white transfer image, for example, the employment of dyedevelopers of the three subtractive colors in an appropriate mixture inwhich the quantities of the dye developers are proportioned such thatthe colors combine to provide black.

Where in the specification, the expression positive image has been used,this expression should not be interpreted in a restrictive sense sinceit is used primarily for purposes of illustration, in that it definesthe image produced on the image-carrying layer as being reversed, in thepositive-negative sense, with respect to the image in the photosensitiveemulsion layers. As an example of an alternative means for for positiveimage, assume that the photosensitive element is exposed to actiniclight through a negative transparency. In this case, the latent image inthe photosensitive emulsion layers will be a positive and the dye imageproduced on the imagecarrying layer will be a negative. The expressionpositive image is intended to cover such an image produced on theimage-carrying layer.

'It will be recognized that, by reason of the preferred film unitsstructural parameters, the transfer image formed upon direct exposure ofthe film unit to a selected subject and processing, will be ageometrically reversed image of the subject. Accordingly, to providetransfer image formation geometrically nonreversed, exposure of suchfilm unit should be accomplished through an image reversing opticalsystem such a camera possessing an image reversing optical system.

In addition to the described essential layers, it will be recognizedthat the film unit may also contain one or more subcoats or layers,which, in turn, may contain one or more additives such as plasticizers,intermediate essential layers for the purpose, for example, of improvingadhesion, and that any one or more of the described layers may comprisea composite of two or more strata of the same, or different, componentsand which may be contiguous, or separated from, each other, for example,two or more neutralizing layers or the like, one of which may bedisposed intermediate the cyan dye image-forming component retaininglayer and the dimensionally stable opaque layer.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

1. A photographic film unit which is adapted to be processed by passingsaid unit between a pair of juxtaposed pressure-applying members andwhich comprises, in combination:

a photosensitive element comprising a composite structure containing, asessential layers, in sequence, a first dimensionally stable, liquidimpermeable layer opaque to incident actinic radiation; a photosensitivesilver halide emulsion layer having associated therewith a dyeimage-forming material which is soluble and diffusible, in alkalineprocessing composition, as a function of silver halide emulsionphotoexposure, at a first solvent concentration; a polymeric layerdyeable by said dye image-providing material; a second dimensionallystable, liquid impermeable layer transparent to incident actinicradiation; and means securing said layers in substantially fixedrelationship; said first and said second dimensionally stable layers,taken together, possessing a processing composition solvent vaporpermeability sufiicient to effect, subsequent to substantial dyetransfer image formation by diffusion transfer processing and precedingsubstantial environmental dye transfer image degradation, osmotictranspiration of processing composition solvent in a quantity effectiveto decrease said first solvent concentration at which said dyeimage-forming material is soluble and diffusible to a second solventconcentration at which said dye image-forming material is substantiallynondifiusible, and

a rupturable container retaining an alkaline processing composition in aquantity sufficient to provide said first solvent concentration and anopacifying agent in a quantity sufficient to mask said dyeimage-providing material fixedly positioned and extending transverse aleading edge of said photosensitive element to effect unidirectionaldischarge of said con tainers alkaline processing composition betweensaid dyeable polymeric layer and the photosensitive silver halideemulsion layer next adjacent thereto.

2. A photographic film unit as defined in claim 1 wherein said firstdimensionally stable layer is transparent to incident actinic radiation.

3. A photographic film unit as defined in claim 2 wherein saidopacifying agent is initially present intermediate said dyeablepolymeric layer and the photosensitive silver halide emulsion layer nextadjacent thereto in a quantity sufficient to mask said dyeimage-providing material.

4. A photographic film unit as defined in claim 1 wherein said solventis water.

5. A photographic film unit as defined in claim 4 wherein said dyeimage-providing material is a dye which is a silver halide developingagent.

6. A photographic film unit as defined in claim 5 wherein said dye issubstantially soluble and ditfusible only in the reduced form at saidfirst solvent concentration and is sub stantially nondiffusible in saidreduced form at said second solvent concentration.

7. A photographic film unit as defined in claim 6 Wherein said liquidimpermeable, dimensionally stable layers comprise flexible polymericsheet materials which possess a water vapor transmission rate at ambienttemperatures and presures averaging not less than about 1 gram of water/24 hrs/ in. /mil thickness.

8. A photographic film unit as defined in claim 7 wherein said liquidimpermeable, dimensionally stable layers comprise flexible polymericsheet materials which possess a water vapor transmission rate at ambienttemperatures and pressures averaging not less than about 100 grams ofwater/ 24 hrs./ 100 in. mil thickness.

9. A photographic film unit as defined in claim 8 wherein at least oneof said flexible polymeric sheet materials comprises liquid impermeable,water vapor permeable cellulose triacetate possessing a water vaportransmission rate at ambient temperatures and pressures averaging not 21less than about 300 grams of water/24 hrs/100 in. /mil thickness.

10. A photographic film unit as defined in claim 8 wherein at least oneof said polymeric sheet materials comprises liquid impermeable, watervapor permeable polyester possessing a water vapor transmission rate atambient temperatures and pressures averaging not less than about 300grams of water/24 hrs./ 1000 in /mil thickness.

11. A photographic film unit as defined in claim 8 wherein saidopacifying agent is present in a quantity sufficient to prevent exposureof said silver halide emulsion during processing in the presence ofradiation actinic thereto and incident on said distributed processingcomposition.

12. A photographic film unit as defined in claim 8 wherein saidopacifying agent is actinic radiation reflective.

13. A photographic film unit as defined in claim 12 wherein saidopacifying agent is titanium dioxide.

14. A photographic film unit as defined in claim 8 wherein said aqueousalkaline composition contains a filmforming polymeric material.

15. A photographic film unit as defined in claim wherein saidphotosensitive element comprises at least two selectively sensitizedsilver halide emulsion layers each having a dye which dye is a silverhalide developing agent of predetermined color associated therewith,each of said dyes soluble and diffusible, in alkaline processingcomposition, at said first solvent concentration.

16. A photographic film unit as defined in claim 15 wherein each of saidselectively sensitized photosensitive silver halide emulsions haspredominant spectral sensitivity to separate regions of the spectrum andthe dye associated with each of said silver halide emulsion layerspossesses a spectral absorption range subsequent to processingsubstantially complementary to the predominant sensitivity range of itsassociated emulsion layer.

17. A photographic film unit as defined in claim 16 wherein each of saidsilver halide emulsion layers and its associated dye is separated fromthe next adjacent silver halide emulsion layer and its associated dye byan alkaline solution permeable polymeric interlayer.

18. A process for forming transfer images in color which comprises, incombination, the steps of:

(a) exposing a photographic film unit which is adapted to be processedby passing the unit between a pair of juxtaposed pressure-applyingmembers and which includes, in combination, a composite structurecomprising a first dimensionally stable, liquid impermeable layer opaqueto incident actinic radiation; a photosensitive silver halide emulsionlayer having associated therewith a dye image-forming material which issoluble and diffusible, in alkaline processing composition, as afunction of silver halide emulsion photoexposure, at a first solventconcentration; a polymeric layer dyeable by said dye image-providingmaterial; a second dimensionally stable, liquid impermeable layertransparent to incident actinic radiation; said first and said seconddimensionally stable layers, taken together, possessing a processingcomposition solvent vapor permeability capacity sufficient to effect,subsequent to substantial dye transfer image formation by diffusiontransfer processing and preceding substantial environmental dye transferimage degradation, osmotic transpiration of processing compositionsolvent in a quantity effective to decrease said first solventconcentration at which said dye image-forming material is soluble anddifiusible to a second solvent concentration at which said dyeimage-forming material is substantially nondiffusible; and meanssecuring said layers in substantially fixed relationship; and

a rupturable container retaining an alkaline processing composition in aquantity sufficient to provide said first solvent concentration and anopacifying agent in a quantity sufiicient to mask said dyeimage-providing material fixedly positioed and extending transverse aleading edge of said photosensitive element to effect unidirectionaldischarge of said containers alkaline processing composition betweensaid dyeable polymeric layer and the photosensitive silver halideemulsion layer next adjacent thereto upon application of compressiveforce to said container;

(b) applying compressive force to said rupturable container to effectunidirectional discharge of said containers alkaline processingcomposition between said dyeable polymeric layer and the photosensitivesilver halide emulsion layer next adjacent thereto, thereby effectingdevelopment of said silver halide emulsion and formation of an imagewisedistribution of mobile dye image-providing material associated with saidemulsion as a function of the pointto-point degree of emulsion exposure;

(c) transferring, by diffusion, at least a portion of said imagewisedistribution of said mobile dye imageproviding material to saidpolymeric layer dyeable by said dye image-forming material to provide adye image thereto in terms of said distribution;

(d) transferring, by osmotic transpiration of alkaline processingcomposition solvent from said composite structure, subsequent tosubstantial dye transfer image formation and preceding substantialenvironmental dye transfer image degradation, a sufiicient portion ofthe solvent of said alkaline processing composition to thereby reducesaid first solvent concentration at which said dye image-formingmaterial is soluble and diffusible to a second solvent concentration atwhich said dye image-forming material is substantially nondiifusible;and

(e) maintaining said composite structure intact subsequent to saidprocessing.

19. A process as defined in claim 18 wherein said first dimensionallystable layer is transparent to actinic radiation.

20. A process as defined in claim 19 wherein said opacifying agent isinitially present intermediate said dyeable polymeric layer and thephotosensitive silver halide emulsion layer next adjacent thereto.

21. A process as defined in claim 18 wherein said solvent is water.

22. A process as defined in claim 21 wherein said dye image-providingmaterial is a dye which is a silver halide developing agent.

23. A process as defined in claim 22 wherein said dye is substantiallysoluble and diffusible only in the reduced form at said first solventconcentration and is substantially nondiifusible in said reduced form atsaid second solvent concentration.

24. A process as defined in claim 22 wherein said liquid impermeable,dimensionally stable layers comprise flexible polymeric sheet materialswhich possess a water vapor transmission rate at ambient temperaturesand pressures averaging not less than about 1 gram of water/24 hrs/ in.mil. thickness.

25. A process as defined in claim 24 wherein said liquid impermeable,dimensionally stable layers comprise flexible polymeric sheet materialswhich possess a water vapor transmission rate at ambient temperaturesand pressures averaging not less than about 100 grams of 'Water/ 24hrs/100 inP/mil thickness.

26. A process as defined in claim 25 wherein at least one of saidflexible polymeric sheet materials comprises liquid impermeable, waterpermeable cellulose triacetate possessing a water vapor transmissionrate at ambient temperatures and pressures averaging not less than about300 grams of water/24 hrs./ 100 in. mil thickness.

27. A process as defined in claim 25 wherein at least one of saidpolymeric sheet materials comprises liquid im- 23 permeable, vaporpermeable polyester possessing a water vapor transmission rate atambient temperatures and pressures averaging not less than about 300grams of water/ 24 hrs/100 in. mil thickness.

28. A process as defined in claim 22 wherein said opacifying agent ispresent in a quantity sufficient to prevent exposure of said silverhalide emulsion during processing in the presence of radiation actinicthereto and incident on said processing composition distributed betweensaid dyeable polymeric layer and said silver halide emulsion layer nextadjacent thereto.

29. A process as defined in claim 22 wherein said opacifying agent isactinic radiation reflective.

30. A process as defined in claim 29 wherein said opacifying agent istitanium dioxide.

31. A process as defined in claim 30 wherein said aqueous alkalinesolution contains a film-forming polymeric material.

32. A process as defined in claim 22 including the step of separatingsaid container from said composite structure subsequent to substantialtransfer image formation.

33. A process for forming transfer images in color which comprises, incombination, the steps of:

(a) exposing a photographic film unit which is adapted to be processedby passage through a pair of juxtaposed pressure-applying members andwhich includes, in combination, a composite structure comprising a firstdimensionally stable, liquid impermeable layer opaque to incidentactinic radiation; at least two selectively sensitized silver halideemulsion layers, each of said silver halide emulsions having associatedtherewith a dye, which is a silver halide developing agent, ofpredetermined color, and is soluble and diffusible, in alkali, at afirst solvent concentration; a polymeric layer dyeable by said dye; asecond dimensionally stable, liquid impermeable layer transparent toincident actinic radiation; said first and said second dimensionallystable layers, taken together, possessing a processing compositionsolvent vapor transmission effective to provide, subsequent tosubstantial dye transfer image formation and preceding substantialenvironmental dye transfer image degradation, osmotic transmission ofthe environmental atmosphere of processing solution solvent vapor in aquantity effective to decrease said first solvent concentration at whichsaid dyes are soluble and diffusible to a second solvent concentrationat which said dyes are substantially nondiffusible; and means securingsaid layers in substantially fixed relationship; and

a rupturable container retaining an alkaline processing solution in aquantity sufficient to provide said first solvent concentration and anopacifying agent in a quantity suflicient to mask 24 said dyes fixedlypositioned and extending transverse a leading edge of saidphotosensitive element to effect discharge of said containers processingsolution between said dyeable polymeric layer and the photosensitivesilver halide emulsion layer next adjacent thereto upon application ofcompressive force to said container;

(b) applying compressive force to said rupturable container to effectdischarge of said containers alkaline processing solution between saiddyeable polymeric layer and the photosensitive silver halide emulsionlayer next adjacent thereto, thereby effecting development of each ofsaid silver halide emulsions, immobilization of the dye associated witheach of said emulsion layers as a result of development, and formationof an imagewise distribution of mobile dye as a function of thepoint-to-point degree of emulsion exposure;

(c) transferring, by imbibition, at least a portion of each of saidimagewise distributions of mobile dyes to said polymeric layer dyeableby said dyes to provide thereto a dye image;

(d) transferring, by osmotic transpiration of processing solutionsolvent vapor from said composite structure, subsequent to substantialdye transfer image formation and preceding said substantialenvironmental dye transfer image degrgadation, a sufficient portion ofthe solvent of said alkaline processing solution to thereby reduce saidfirst solvent concentration at which said dyes are soluble anddiffusible to a second solvent concentration, at which said dyes aresubstantially nondiffusible; and

(e) maintaining said composite structure intact subsequent to saidprocessing.

34. A process as defined in claim 33 wherein each of said selectivelysensitized silver halide emulsion layers possess predominant spectralsensitivity to a separate region of the spectrum and the dye associatedwith each of said emulsion layers possesses a spectral absorption rangesubsequent to processing substantially complementary to the predominantsensitivity range of its associated emulsion.

References Cited UNITED STATES PATENTS 2,647,055 7/1953 Land 96292,740,715 4/1956 Land 9676X 2,839,479 6/1958 Caldwell et al. 1l7135.5X3,165,423 1/1965 Caldwell et a1. 117-135.5 3,376,137 4/1968 Farney 96-3X3,473,925 10/1969 Milligan et al. 9629X WILLIAM D. MARTIN, PrimaryExaminer US. Cl. X.R.

